In a multi-cylinder reciprocating internal combustion engine, there are differences in the amount of useful torque produced by each cylinder, even during normal operation. Small between-cylinder torque differences can cause rough idling and poor emissions performance. Large between-cylinder differences, such as those caused by damaged piston rings, burned valves, holes in the cylinder head and liners, etc., can cause extremely rough operation. The process for sensing these torque differences and using the information for compensation or diagnosis of engine operation is known as cylinder balancing.
In the prior art, the diagnosis of low engine power and individual cylinder power problems has typically required a combination of: 1) exhaust temperature measurements to isolate the faulty cylinder, 2) fuel injector changes and overhead resetting to further isolate the nature of the problem, and 3) partial engine disassembly to inspect sealing components such as valves, valve seats, piston rings, and liners. All of these methods are very labor intensive and therefore costly and inconvenient. There is therefore a need for a method which very quickly identifies individual cylinder compression problems with no hardware disassembly, which will lead to faster and more cost-effective diagnosis and repair, as well as early warning of worsening compression imbalance. The present invention is directed toward meeting this need.